PERFECT SOCIETIES OF INSECTS. 133 



the workers in length, he thinks that this may arise 

 from their being of a substance too stiff to admit of their 

 extension. Those parts and points that were in a state 

 to yield most easily to the action which this kind of nu- 

 triment produced, would be most prominent; and the 

 vertical position of the grub and pupa, since nature does 

 nothing in vain, may probably assist this action, and 

 render the parts of the animal more capable of such ex- 

 tension than if it continued in a horizontal position. 



We know, with respect to the human species and the 

 larger animals, that numerous differences, both as to the 

 form and relative proportion of parts, occur continually. 

 The cause of these differences we cannot always ascer- 

 tain ; yet in many instances they may either be derived 

 from the nutriment which the embryo receives in the 

 womb, or from the greater or less dimensions or higher 

 or lower temperature of that organ — a case that analogi- 

 cally would not be very wide of that of the grub or em- 

 bryo of a bee inclosed in a cell. Some of the differences 

 in man T now allude to, may often be caused by a par- 

 ticular diet in childhood ; a warmer or a colder, a looser 

 or a tighter dress, or the like. Thus, for instance, the 

 Egyptians, who went bare-headed, had their skulls re- 

 markably thick ; while the Persians, who covered the 

 head with a turban or mitre, were distinguished by the 

 tenuity of theirs. Again, the inhabitants of certain di- 

 stricts are often remarkable for peculiarities of form, which 

 are evidently produced by local circumstances. 



The following reasoning may not be inapplicable to 

 the development or non-development, according to their 

 food and habitation, of the ovaries of these insects. An 

 infant tightly swathed, as was formerly the custom, in 



